Production of Polysilicon using a Modified Siemens Process

4. High boiling impurities exit at the bottom of the column
Post-condition: The desired compound is isolated at a certain purity level and passed
onto the next step in the reaction
Scenario (1.2.1): Separation of H2
Description: H2 is removed from the FBR products
Primary Object: Flash Distillation Drum
Primary Actors: H2, TCS,TET, BCl3, P2Cl5
Pre-condition: Inputs are fed in at proper conditions and the distillation drum is
maintained at proper conditions
Flow of Events:
1. FBR products are fed into drum
2. Products cooled until only H2 remains as gas
3. H2 exits and other compounds are isolated
Post-condition: All H2 is removed from the FBR product stream. The H2-free
stream continues through the rest of the process. The removed H2 is
recycled for use later in the process.
Scenario (1.2.2): Separation of BCl3
Description: BCl3 is removed from the H2 separation products
Primary Object: Distillation Column
Primary Actors: TCS,TET, BCl3, P2Cl5
Pre-condition: Inputs are fed in at proper conditions and the
distillation column is maintained at proper conditions
Flow of Events:
4. H2 separation products are fed into column
5. H2 separation column products undergo reflux
6. BCl3 boils most easily and exits at the top of the column, with a small
amount of other compounds
7. Other compounds exit at the bottom of the column